An electro-deposition system may include an electrode immersed in a solution of coating material, solvent and a neutralizing agent. As the coating material is deposited on the surface of the electrode, the supply of coating material in solution must be replenished. Otherwise, the concentration of neutralizing agent in the solution may increase and create xe2x80x9cpin-holexe2x80x9d defects in the electro-deposition coating. An electro-deposition system for solving this problem is described in U.S. application Ser. 09/183,547, now U.S. Pat. No. 6,264,809 to Cheng H. Lee (the xe2x80x9cLee systemxe2x80x9d).
In an embodiment of the Lee system, a tubular electrode is enclosed in a tubular membrane assembly. The tubular membrane assembly may consist of an outer frame and an inner guide, between which is contained a permeable membrane. The inner and outer walls may be made of a non-permeable rigid material and may include apertures through which coating material may pass. The coating material may pass through a window in the outer wall of the frame, permeate through the membrane and then pass through a window in the inner wall of the frame. Upon passing through the tubular membrane assembly, the coating material may dissolve into the solution in which the electrolyte is immersed.